A motor power supply circuit control device

Abstract

The utility model relates to motor power supply control technical field discloses a kind of motor power supply loop control device, install on the power supply loop between motor and power supply, including circuit breaker, contactor, relay and motor protector. Among them, power supply, circuit breaker, contactor main contact are sequentially connected with motor;The voltage signal input port of motor protector is connected circuit breaker output port;Pulsed normally open relay output port is connected with the coil of contactor through relay normally open contact and forms loop, and contactor auxiliary contact and pulsed normally open relay output port are parallelly connected;Fault tripping port is connected with relay coil. The present application improves internal circuit structure, solves the problem that power supply control loop cannot be self-kept when motor protector is dead in the existing device, and motor misoperation tripping, ensures that motor stable operation is not affected when motor protector fails, and improves the safety of unit operation.

Description

Technical Field

[0001] This utility model relates to the field of motor power supply control technology, specifically a motor power supply circuit control device. Background Technology

[0002] In motor power supply systems, the stable operation and safety of the motor are key factors in ensuring the reliability and efficiency of the entire system. Traditional motor power supply circuit control devices, including basic components such as circuit breakers, contactors, and motor protectors, can meet basic power supply control requirements, but they often show deficiencies in protection and support when faced with complex operating environments and fault conditions.

[0003] The design philosophy of motor protectors is to serve the protected object, namely the motor. Therefore, when the motor itself malfunctions, it should not cause the motor to trip unnecessarily. However, in currently used motor power supply circuit control devices, the connection method between the motor protector and other components such as contactors has a design flaw. This leads to a situation where, when the motor protector malfunctions, the power supply control circuit cannot self-hold, causing the motor to trip unnecessarily. This forces the unit to operate at reduced load, seriously threatening the safe operation of the unit.

[0004] In response to this situation, it is urgent to change the internal circuit structure of the existing motor power supply circuit control device to ensure that the motor protector will not affect the stable operation of the motor when a fault occurs. Utility Model Content

[0005] To overcome the problems existing in related technologies, this utility model provides a motor power supply circuit control device. This device improves the internal circuit structure to ensure that the motor will not trip erroneously when the motor protector fails, thereby ensuring the safety and reliability of the entire motor power supply system.

[0006] The technical solution adopted by this utility model is: a motor power supply circuit control device, installed on the power supply circuit between the motor and the power source, including a circuit breaker, a contactor, a relay and a motor protector;

[0007] The contactor includes a main contactor contact, a normally open auxiliary contactor contact, and a contactor coil; the relay includes a normally open contactor contact and a relay coil; and the motor protector includes a voltage signal input port, a pulse-type normally open relay output port, and a fault trip port.

[0008] The power supply is connected to the circuit breaker input port, the circuit breaker output port is connected to the contactor main contact input port, and the contactor main contact output port is connected to the motor power supply input port.

[0009] The voltage signal input port is connected to the output port of the circuit breaker;

[0010] The pulse-type normally open relay output port includes a first contact and a second contact. The first contact is connected to the positive terminal of the power supply, and the second contact is connected to one end of the normally open contact of the relay. The other end of the normally open contact of the relay is connected to the A1 terminal of the contactor coil, and the A2 terminal of the contactor coil is connected to the negative terminal of the power supply. One end of the normally open auxiliary contact of the contactor is connected to the first contact, and the other end of the normally open auxiliary contact of the contactor is connected to the second contact.

[0011] The fault trip port includes a first trip contact and a second trip contact. The first trip contact is connected to the positive terminal of the power supply, and the second trip contact is connected to one end of the relay coil. The other end of the relay coil is connected to the negative terminal of the power supply.

[0012] Furthermore, the power supply is a three-phase four-wire power supply, including phase line L1, phase line L2, phase line L3 and neutral line N, and the circuit breaker input port includes a first circuit breaker input contact, a second circuit breaker input contact and a third circuit breaker input contact.

[0013] The L1 phase line is connected to the input contact of the first circuit breaker, the L2 phase line is connected to the input contact of the second circuit breaker, and the L3 phase line is connected to the input contact of the third circuit breaker.

[0014] Furthermore, the circuit breaker output port includes a first circuit breaker output contact, a second circuit breaker output contact, and a third circuit breaker output contact; the contactor main contact input port includes a first contactor main contact input contact, a second contactor main contact input contact, and a third contactor main contact input contact; and the contactor main contact output port includes a first contactor main contact output contact, a second contactor main contact output contact, and a third contactor main contact output contact.

[0015] The first circuit breaker output contact is connected to the first contactor main contact input contact, the second circuit breaker output contact is connected to the second contactor main contact input contact, and the third circuit breaker output contact is connected to the third contactor main contact input contact.

[0016] The main contact output contacts of the first contactor, the second contactor, and the third contactor are respectively connected to the motor power input port.

[0017] Furthermore, the voltage signal input port includes a Ua port, a Ub port, a Uc port, and an Un port. The Ua port is connected to the output contact of the first circuit breaker, the Ub port is connected to the output contact of the second circuit breaker, the Uc port is connected to the output contact of the third circuit breaker, and the Un port is connected to the N neutral line.

[0018] Furthermore, the first contact is connected to the L1 phase line via a wire connected in series with the first switch, and the A2 end of the contactor coil is connected to the N neutral line.

[0019] Furthermore, the first trip contact is connected to the first switch, and the other end of the relay coil is connected to the N neutral line.

[0020] Furthermore, the motor protector also includes a control signal input port, which includes a closing command input port. The closing command input port is connected to the DCS system signal via a signal line, and the closing command input port is connected to the first switch via a wire connected in series with a second switch.

[0021] Furthermore, the control signal input port also includes a trip command input port, which is connected to the DCS system signal via a signal line, and is connected to the first switch via a wire with a third switch connected in series.

[0022] Furthermore, the motor protector is also equipped with a device fault alarm port, which is a normally closed port and is connected to the DCS system signal.

[0023] Furthermore, the motor protector is also equipped with an operation display unit interface, which is connected to a touch screen.

[0024] The motor power supply circuit control device of this utility model has the following technical effects: (I) Optimizes the circuit structure and constructs an electrical interlocking self-holding structure. The power supply, circuit breaker, contactor and motor protector form a closed-loop control link. The voltage signal input port monitors the voltage status of the circuit breaker output terminal in real time, providing accurate operating parameters for the motor protector, enabling it to judge the system operating condition in a timely manner. One end of the contactor auxiliary contact is connected to the first contact of the output port of the pulse-type normally open relay of the motor protector, and the other end is connected to the second contact of the output port of the pulse-type normally open relay of the motor protector. The second contact is connected to the normally open auxiliary contact of the relay and the contactor coil in sequence through wires and then connected to the N neutral line. This structure does not rely on the continuous pulse output of the motor protector. Only in the initial stage of closing does the motor protector need to provide a pulse signal to trigger the action of the normally open auxiliary contact of the contactor. Subsequently, the normally open auxiliary contact of the contactor maintains the conduction of the control circuit, reducing the dependence on the continuous operation of the motor protector and improving the stability of the control circuit under complex operating conditions.

[0025] (II) The independent connection between the fault trip port and the relay coil forms a "rapid fault disconnection channel." When the motor protector itself malfunctions (such as freezing or abnormal signal), because the fault trip port is a normally closed port, and the first and second trip contacts are also normally closed, the connection between the first and second trip contacts will not be accidentally triggered and disconnected due to power loss caused by a motor protector malfunction, thus avoiding false motor tripping due to a motor protector malfunction. However, when a real fault occurs in the motor or power supply circuit, the fault trip port will be energized and disconnected. Consequently, the relay coil will be de-energized, the normally open contact of the relay will open, the contactor coil will be de-energized, and the main contact of the contactor will open. In this way, the power supply circuit of the motor is disconnected, achieving rapid fault isolation, preventing the fault from escalating, and ensuring the safety of the motor and the entire power supply system.

[0026] Other features and advantages disclosed in this utility model will be described in detail in the following detailed description section. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is an overall structural block diagram of a motor power supply circuit control device according to an exemplary embodiment.

[0029] Reference numerals: 10, Motor power supply circuit control device; 20, Motor; 30, Circuit breaker; 40, Contactor; 41, Contactor main contact; 42, Contactor normally open auxiliary contact; 43, Contactor coil; 50, Relay; 51, Relay normally open contact; 52, Relay coil; 60, Motor protector; 61, Voltage signal input port; 611, Ua port; 612, Ub port; 613, Uc port; 614, Un port; 62, Pulse-type normally open relay output port; 621, First... Contact; 622, Second contact; 63, Fault trip port; 631, First trip contact; 632, Second trip contact; 64, Closing command input port; 65, Trip command input port; 66, Device fault alarm port; 67, Operation display unit interface; 70, Three-phase four-wire power supply; 71, L1 phase line; 72, L2 phase line; 73, L3 phase line; 74, N neutral line; 80, DCS system; 90, Touch screen; 101, First switch; 102, Second switch; 103, Third switch. Detailed Implementation

[0030] The specific embodiments disclosed herein will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this disclosure.

[0031] like Figure 1 The diagram shows a disclosed exemplary embodiment of the present invention. The motor power supply circuit control device 10 of the present invention is installed on the power supply circuit between the motor 20 and the power source, and includes: a circuit breaker 30, a contactor 40, a relay 50, and a motor protector 60. The contactor 40 includes a contactor main contact 41, a contactor normally open auxiliary contact 42, and a contactor coil 43; the relay 50 includes a relay normally open contact 51 and a relay coil 52; and the motor protector 60 includes a voltage signal input port 61, a pulse-type normally open relay output port 62, and a fault trip port 63.

[0032] The power supply is connected to the input port of circuit breaker 30, the output port of circuit breaker 30 is connected to the input port of contactor main contact 41, and the output port of contactor main contact 41 is connected to the power input port of motor 20. In this way, a power circuit is formed between the power supply, circuit breaker 30, contactor main contact 41, and motor 20.

[0033] The voltage signal input port 61 is connected to the output port of the circuit breaker 30.

[0034] The pulse-type normally open relay output port 62 includes a first contact 621 and a second contact 622. The first contact 621 is connected to the positive terminal of the power supply, and the second contact 622 is connected to one end of the normally open contact 51 of the relay. The other end of the normally open contact 51 is connected to the A1 terminal of the contactor coil 43, and the A2 terminal of the contactor coil 43 is connected to the negative terminal of the power supply. One end of the normally open auxiliary contact 42 of the contactor is connected to the first contact 621, and the other end of the normally open auxiliary contact 42 is connected to the second contact 622. This forms a control circuit and constructs an electrically interlocked self-holding structure.

[0035] The fault trip port 63 includes a first trip contact 631 and a second trip contact 632. The first trip contact 631 is connected to the positive terminal of the power supply, and the second trip contact 632 is connected to one end of the relay coil 52. The other end of the relay coil 52 is connected to the negative terminal of the power supply. In this way, an independent fault disconnection circuit is formed.

[0036] In the motor power supply circuit control device 10 of this utility model, the power supply, circuit breaker 30, contactor main contact 41, and motor 20 form a power-on circuit, and are electrically connected through the input / output ports of circuit breaker 30 and contactor main contact 41. Contactor main contact 41, as the switching element of the power-on circuit, can control the start and stop of motor 20 through electrical signals. Circuit breaker 30, as the first line of protection for the main circuit, can automatically cut off the power supply when abnormal currents such as short circuits or overloads occur in the circuit, preventing damage to motor 20 or wiring due to abnormal current.

[0037] The voltage signal input port 61 of the motor protector 60 is connected to the output port of the circuit breaker 30 to monitor the voltage status at the downstream end of the circuit breaker 30 in real time; it provides voltage-level protection for the operation of the motor 20, and avoids the motor 20 from operating under abnormal voltage, which may lead to shortened life or failure.

[0038] In an exemplary embodiment of this disclosure, the fault trip port 63 adopts a normally closed design, and its first trip contact 631 and second trip contact 632 remain closed under normal conditions, similar to the normally closed contact characteristics of a relay. This ensures that the fault disconnection circuit is always in a conducting state under normal conditions, and the relay coil 52 is continuously energized, thereby ensuring that the normally open contact 51 of the relay remains closed.

[0039] The pulse-type normally open relay output port 62 of the motor protector 60 is a normally open pulse signal port. When activated, it receives a pulse signal with a duration of 3 seconds, causing the first contact 621 and the second contact 622 to close, and automatically open after 3 seconds. When the first contact 621 and the second contact 622 are closed, the current flows along the path of "positive power supply → first contact 621 → second contact 622 → normally open relay contact 51 (normally closed) → contactor coil 43 → negative power supply", and the control circuit is immediately connected. After the contactor coil 43 is energized, it drives the contactor main contact 41 to close, connecting the energizing circuit consisting of the power supply, circuit breaker 30, contactor main contact 41, and motor 20, and the motor 20 starts running. At the same time, the normally open auxiliary contact 42 of the contactor also closes due to the energization of the contactor coil 43. After the first contact 621 and the second contact 622 are disconnected, the current path switches to "positive power supply → normally open auxiliary contact 42 of the contactor (closed) → normally open contact 51 of the relay (normally closed) → contactor coil 43 → negative power supply", realizing the self-holding function of the control circuit and maintaining the continuous conduction of the energized circuit. Compared with the traditional control method that relies on continuous pulse signals, this reduces the requirement for the continuity of the control signal, improves system stability, and reduces the probability of control circuit failure.

[0040] The first trip contact 631 is connected to the positive terminal of the power supply, and the second trip contact 632 is connected to the relay coil 52, forming an independent fault disconnection circuit. When the motor protector 60 detects a fault in the motor 20 (such as overload, phase loss, or overheating), the fault trip port 63 is triggered, the first trip contact 631 and the second trip contact 632 disconnect, the relay coil 52 is de-energized, causing the normally open contact 51 of the relay to open (in the control circuit), cutting off the power supply to the contactor coil 43, and the contactor main contact 41 to open, immediately de-energizing the motor 20. However, when the motor protector 60 malfunctions and loses power due to its own fault, because the fault trip port 63 is a normally closed design, it is only triggered to open when activated by internal energization. Therefore, the first trip contact 631 and the second trip contact 632 remain closed at this time, and will not affect the control circuit or the energizing circuit. This solves the problem in the prior art where the power supply control circuit cannot maintain its position when the motor protector 60 malfunctions. This ensures the safety and reliability of the entire motor 20 power supply system.

[0041] For example, such as Figure 1As shown, in the exemplary embodiment disclosed in this utility model, the power supply is a three-phase four-wire power supply 70, including L1 phase line 71, L2 phase line 72, L3 phase line 73 and N neutral line 74. The circuit breaker 30 input port includes a first circuit breaker 30 input contact, a second circuit breaker 30 input contact and a third circuit breaker 30 input contact. L1 phase line 71 is connected to the first circuit breaker 30 input contact, L2 phase line 72 is connected to the second circuit breaker 30 input contact, and L3 phase line 73 is connected to the third circuit breaker 30 input contact.

[0042] The circuit breaker 30 output port includes a first circuit breaker 30 output contact, a second circuit breaker 30 output contact, and a third circuit breaker 30 output contact. The contactor main contact 41 input port includes a first contactor main contact 41 input contact, a second contactor main contact 41 input contact, and a third contactor main contact 41 input contact. The contactor main contact 41 output port includes a first contactor main contact 41 output contact, a second contactor main contact 41 output contact, and a third contactor main contact 41 output contact.

[0043] The output contact of the first circuit breaker 30 is connected to the input contact of the first contactor main contact 41, the output contact of the second circuit breaker 30 is connected to the input contact of the second contactor main contact 41, and the output contact of the third circuit breaker 30 is connected to the input contact of the third contactor main contact 41. The output contacts of the first, second, and third contactor main contacts 41 are respectively connected to the power input port of the motor 20.

[0044] In the exemplary embodiments of this disclosure, the power supply adopts a three-phase four-wire system. The circuit breaker 30, the contactor main contacts 41, and the motor 20 are each provided with corresponding contacts and ports, which are connected one-to-one with the three phases of the power supply. The three-phase four-wire power supply 70 can provide a more stable power output. Compared with a single-phase power supply, it can transmit more power with the same conductor cross-sectional area, making it suitable for high-power motor 20 loads and reducing line losses. By independently connecting the three phase lines, the load of the motor 20 can be evenly distributed to the three-phase power supply, avoiding power imbalance problems caused by excessive single-phase loads and reducing the risk of grid fluctuations. The three input contacts and three output contacts of the contactor main contacts 41 close / open synchronously, ensuring that the three-phase windings of the motor 20 are energized / de-energized simultaneously, avoiding starting torque imbalance or running vibration caused by phase inconsistency, ensuring the smooth and efficient operation of the motor 20, and forming a fault linkage protection.

[0045] For example, such as Figure 1As shown, in an exemplary embodiment of the present invention, the voltage signal input port 61 includes a Ua port 611, a Ub port 612, a Uc port 613, and an Un port 614. The Ua port 611 is connected to the output contact of the first circuit breaker 30, the Ub port 612 is connected to the output contact of the second circuit breaker 30, the Uc port 613 is connected to the output contact of the third circuit breaker 30, and the Un port 614 is connected to the N neutral line 74.

[0046] In the exemplary embodiments of this disclosure, the combination of the three-phase port and the neutral port enables comprehensive sampling of the line voltage and phase voltage of a three-phase four-wire circuit. Real-time acquisition of the amplitude, phase, and waveform differences of each phase voltage provides data support for accurate location of subsequent faults such as voltage imbalance, phase loss, and overvoltage / undervoltage. Power is drawn from the output contacts of the circuit breaker 30, utilizing its overload protection characteristics to prevent hardware damage due to overcurrent or overvoltage when the voltage signal input port 61 is directly connected to the power grid.

[0047] For example, such as Figure 1 As shown, in an exemplary embodiment of this utility model, the first contact 621 is connected to the L1 phase line 71 via a wire connected in series with the first switch 101, and the A2 end of the contactor coil 43 is connected to the N neutral line 74. The first trip contact 631 is connected to the first switch 101, and the other end of the relay coil 52 is connected to the N neutral line 74.

[0048] In an exemplary embodiment of this disclosure, a first switch 101 is connected in series between the first contact 621 and the L1 phase line 71, serving as the main power switch for the control circuit and the fault disconnection circuit. Through the first switch 101, the power supply to the control circuit and the fault disconnection circuit can be directly interrupted without going through other control links of the motor protector 60, causing the contactor coil 43 and the relay coil 52 to be simultaneously de-energized. The contactor main contact 41 quickly disconnects the power supply to the motor 20, resulting in a faster fault response and preventing the fault from escalating. Simultaneously, during routine equipment maintenance and repair, disconnecting the first switch 101 can cut off the connection between the L1 phase line 71 and the control circuit and the fault disconnection circuit, avoiding the risk of electric shock caused by live operation and improving the safety of equipment maintenance.

[0049] For example, such as Figure 1As shown in the exemplary embodiment disclosed in this utility model, the motor protector 60 further includes a control signal input port, which includes a closing command input port 64. The closing command input port 64 is connected to the DCS system 80 via a signal line, and is also connected to the first switch 101 via a wire connected in series with the second switch 102. The control signal input port also includes a tripping command input port 65, which is connected to the DCS system 80 via a signal line, and is also connected to the first switch 101 via a wire connected in series with the third switch 103.

[0050] The closing command input port 64 and the tripping command input port 65 are connected to the DCS system 80 via signal lines to enable remote control by the DCS system 80. Simultaneously, the closing command input port 64 is connected to the first switch 101 via a wire connected in series with the second switch 102, and the tripping command input port 65 is connected to the first switch 101 via a wire connected in series with the third switch 103, enabling manual control on-site.

[0051] When the DCS system 80 sends a closing signal, or the second switch 102 closes, connecting the circuit of the first switch 101 and the closing command input port 64, the output port 62 of the pulse-type normally open relay will be activated, so that it receives a 3-second pulse signal, thereby closing the first contact 621 and the second contact 622 for 3 seconds.

[0052] When the DCS system 80 sends a trip signal, or the third switch 103 closes, connecting the circuit between the first switch 101 and the trip command input port 65, the fault trip port 63 will be activated. The first trip contact 631 and the second trip contact 632 will be disconnected, the relay coil 52 will be de-energized, causing the normally open contact 51 of the relay to open (in the control circuit), cutting off the power supply to the contactor coil 43, the main contact 41 of the contactor will open, and the motor 20 will be immediately de-energized.

[0053] For example, such as Figure 1 As shown, in the exemplary embodiment disclosed in this utility model, the motor protector 60 is further provided with a device fault alarm port 66, which is a normally closed port and is connected to the DCS system 80 via signal.

[0054] In the exemplary embodiments of this disclosure, the device fault alarm port 66 is a normally closed port, which can be either actively closed or passively closed. Passively closed: When the motor protector 60 itself malfunctions (e.g., freezes, internal circuit malfunction, signal processing module failure), the internal coil of the motor protector 60 loses power, causing the device fault alarm port 66 to close. The fault alarm circuit is then activated, sending a signal to the DCS system 80. Actively closed: When the motor protector 60 detects abnormal operation of the motor 20 (e.g., overload, underload, phase loss, overheating), the motor protector 60 actively cuts off the power supply to the motor 20, and simultaneously de-energizes the internal coil, causing the device fault alarm port 66 to close. In this case, the fault alarm circuit is also activated, sending an alarm signal to the DCS system 80.

[0055] For example, such as Figure 1 As shown in the exemplary embodiment disclosed in this utility model, the motor protector 60 is further provided with an operation display unit interface 67, which is connected to a touch screen 90; it can display key parameters and fault information of the motor protector 60 and the motor 20 in real time.

[0056] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0057] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0058] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A motor power supply circuit control device, installed on the power supply circuit between the motor and the power source, characterized in that, include: Circuit breakers, contactors, relays, and motor protectors; The contactor includes a main contactor contact, a normally open auxiliary contactor contact, and a contactor coil; the relay includes a normally open contactor contact and a relay coil; and the motor protector includes a voltage signal input port, a pulse-type normally open relay output port, and a fault trip port. The power supply is connected to the circuit breaker input port, the circuit breaker output port is connected to the contactor main contact input port, and the contactor main contact output port is connected to the motor power supply input port. The voltage signal input port is connected to the output port of the circuit breaker; The pulse-type normally open relay output port includes a first contact and a second contact. The first contact is connected to the positive terminal of the power supply, and the second contact is connected to one end of the normally open contact of the relay. The other end of the normally open contact of the relay is connected to the A1 terminal of the contactor coil, and the A2 terminal of the contactor coil is connected to the negative terminal of the power supply. One end of the normally open auxiliary contact of the contactor is connected to the first contact, and the other end of the normally open auxiliary contact of the contactor is connected to the second contact. The fault trip port includes a first trip contact and a second trip contact. The first trip contact is connected to the positive terminal of the power supply, and the second trip contact is connected to one end of the relay coil. The other end of the relay coil is connected to the negative terminal of the power supply.

2. The motor power supply circuit control device according to claim 1, characterized in that, The power supply is a three-phase four-wire power supply, including phase line L1, phase line L2, phase line L3 and neutral line N. The circuit breaker input port includes a first circuit breaker input contact, a second circuit breaker input contact and a third circuit breaker input contact. The L1 phase line is connected to the input contact of the first circuit breaker, the L2 phase line is connected to the input contact of the second circuit breaker, and the L3 phase line is connected to the input contact of the third circuit breaker.

3. The motor power supply circuit control device according to claim 2, characterized by The circuit breaker output port includes a first circuit breaker output contact, a second circuit breaker output contact, and a third circuit breaker output contact; the contactor main contact input port includes a first contactor main contact input contact, a second contactor main contact input contact, and a third contactor main contact input contact; and the contactor main contact output port includes a first contactor main contact output contact, a second contactor main contact output contact, and a third contactor main contact output contact. The first circuit breaker output contact is connected to the first contactor main contact input contact, the second circuit breaker output contact is connected to the second contactor main contact input contact, and the third circuit breaker output contact is connected to the third contactor main contact input contact. The main contact output contacts of the first contactor, the second contactor, and the third contactor are respectively connected to the motor power input port.

4. The motor power supply circuit control device according to claim 2, characterized by The voltage signal input ports include a Ua port, a Ub port, a Uc port, and an Un port. The Ua port is connected to the output contact of the first circuit breaker, the Ub port is connected to the output contact of the second circuit breaker, the Uc port is connected to the output contact of the third circuit breaker, and the Un port is connected to the N neutral line.

5. The motor power supply circuit control device according to claim 2, characterized by The first contact is connected to the L1 phase line via a wire connected in series with the first switch, and the A2 terminal of the contactor coil is connected to the N neutral line.

6. The motor power supply circuit control device according to claim 5, characterized in that, The first trip contact is connected to the first switch, and the other end of the relay coil is connected to the N neutral line.

7. The motor power supply circuit control device according to claim 5, characterized in that, The motor protector also includes a control signal input port, which includes a closing command input port. The closing command input port is connected to the DCS system signal via a signal line, and the closing command input port is connected to the first switch via a wire connected in series with a second switch.

8. The motor power supply circuit control device according to claim 7, characterized in that, The control signal input port also includes a trip command input port, which is connected to the DCS system signal via a signal line, and is connected to the first switch via a wire with a third switch connected in series.

9. The motor power supply circuit control device according to claim 7, characterized in that, The motor protector is also equipped with a device fault alarm port, which is a normally closed port and is connected to the DCS system signal.

10. The motor power supply circuit control device according to claim 1, characterized by The motor protector is also equipped with an operation display unit interface, which is connected to a touch screen.

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